Selection method for additives in photopolymers

ABSTRACT

The invention relates to a method for selecting compounds which can be used as additives in photopolymer formulations for producing light holographic media, and to photopolymer formulations which contain at least one softener which are selected according to the claimed method. The invention also relates to the use of photopolymer formulations for producing holographic media.

The invention relates to a method for selecting compounds which can beused as additives in photopolymer formulations for the production oflight holographic media, and photopolymer formulations which contain atleast one plasticizer which was selected by the method according to theinvention.

WO 2008/125229 A1 describes photopolymer formulations of the typementioned at the outset. These comprise polyurethane-based matrixpolymers, acrylate-based writing monomers and photoinitiators. In thecured state, the writing monomers and the photoinitiators are embeddedwith spatial distribution in the polyurethane matrix. The WO documentlikewise discloses the addition of dibutyl phthalate, a classicalplasticizer for industrial plastics, to the photopolymer formulation.

For uses of photopolymer formulations in the fields of use describedbelow, the refractive index modulation Δn produced by the holographicexposure in the photopolymer plays the decisive role. During theholographic exposure, the interference field of signal and referencelight beam (in the simplest case the two plane waves) is mapped by thelocal photopolymerization of, for example, highly refracting acrylatesat sites of high intensity in the interference field into a refractiveindex grating. The refractive index grating in the photopolymer (thehologram) contains all information of the signal light beam. Byilluminating the hologram only with the reference light beam, the signalcan then be reconstructed. The strength of the signal thus reconstructedin relation to the strength of the reference light used is referred toas diffraction efficiency, DE below. In the simplest case of a hologramwhich forms from the superposition of two plane waves, the DE isobtained from the quotient of the intensity of the light diffracted onreconstruction and the sum of the intensities of incident referencelight and diffracted light. The higher the DE, the more efficient is ahologram with respect to the necessary quantity of reference light whichis required for making the signal visible with a fixed brightness.Highly refractive acrylates are capable of producing refractive indexgratings having a high amplitude between regions having the lowestrefractive index and regions having the highest refractive index andhence of permitting holograms having a high DE and high Δn inphotopolymer formulations. It should be noted that the DE is dependenton the product of Δn and the photopolymer layer thickness d. The largerthe product, the greater is the possible DE (for reflection holograms).The width of the angular range in which the hologram is visible(reconstructed), for example on monochromatic illumination, depends onlyon the layer thickness d. On illumination of the hologram with, forexample, white light, the width of the spectral range which cancontribute to the reconstruction of the hologram likewise depends onlyon the layer thickness d. It is true that the smaller d is the greaterare the respective acceptance widths. It is therefore intended toproduce bright and easily visible holograms, a high Δn·d and a smallthickness d should be strived for in particular so that DE is as largeas possible. This means that the higher Δn is, the more latitude isachieved for configuring bright holograms by adjusting d and withoutloss of DE. The optimization of Δn on the optimization of photopolymerformulations is therefore of outstanding importance (ref. HariharanOptical Holography).

One possibility for achieving as large a Δn as possible is the use ofphotopolymer formulations which contain plasticizers having no opticalrefraction, i.e. those having a low refractive index. In addition to theoptical properties, a further important selection criterion for suchplasticizers is that they must have sufficiently low volatility undertypical production conditions for photopolymer formulations. Owing to anobserved loss of mass in the production of the holographic film media,an obvious presumption is that evaporation of individual componentsmight occur during the production, especially in the area of drying.However, on consideration of the boiling points and of the vapourpressures of the components used, it was not expected that these shouldbe a cause for the evaporation at the respective drying temperatures andhence a reason for the substantially lower Δn values.

However, the vapour pressure is a parameter with the aid of which thesuitability of components for use in the industrial production ofholographic media cannot be tested. This is because the vapour pressureof a chemical compound is a physical constant which describes how a puresubstance or a mixture of substances is in thermodynamic equilibriumwith its liquid or solid phase. For dynamic systems, however, the vapourpressure provides no guidance.

Thus, the vapour pressure does not describe the situation whichprevails, for example, in a continuously operated coating unit in whichthe material applied with a small layer thickness, distributed over alarge surface by air circulation which ensures that the gaseous phase isconstantly removed, is dried.

Expediently, the volatility is considered instead of the vapourpressure. Since this value is difficult to determine experimentally,theoretical methods could be readily applied for this purpose.

Methods in which, based on simple molecular descriptors, relationshipsbetween the molecular properties and the physical properties ofsubstance, referred to below as Quantitative Structure PropertyRelationships (QSPR), are sought and known in principle from theliterature. Thus, for example, Ha et al. (Energy & Fuels, 19, 152,(2005)) describe QSPR models which are suitable for estimating boilingpoints, relative densities and refractive indices of saturated andaromatic hydrocarbons without heteroatoms. Liu et al. have presented aQSPR model which is suitable primarily for fluorine andsulphur-containing hydrocarbons (J. Micro/Nanolith. MEMS MOEMS 7,023001-1-023001-11, (2008)). These models are derived on the basis of alarge set of experimental data and frequently permit a high degree ofpredictability for compounds which are sufficiently similar to thesubstances used for the preparation but have a significantly reducedaccuracy when the similarity is not present.

Further known methods for estimating molecular properties are groupcontribution methods which divide the given molecule into “groups” towhich a certain incremental contribution to a given physical property isassigned. The physical properties are then obtained by summing the groupcontributions. An example is the method published in 2001 by Marrero andGani (Fluid Phase Equilib. 183-184, 183-208 (2001)). However, aprinciple problem of this method is the fact that it is not possible totreat compounds whose molecular structure contains groups not covered bythe method. Moreover, the accuracy is typically not sufficient forquantitative conclusions.

WO 02/051263 and DE 10065443 describe QSPR methods which are based ondescriptors derived from quantum chemical calculations. The method isused there to describe the phase behaviour of aromas or fragrances inmultimaterial systems. These descriptors are suitable in particular fordescribing a versatile set of molecules, so that it is possible to findQSPR models with very few descriptors which can be used in a versatilemanner.

It was an object of the present invention to provide a selection methodfor additives in photopolymer formulations which permit production ofholograms having a relatively high brightness.

The object is achieved, in the method according to the invention if therefractive index and the volatility, expressed as TGA95 value, of agiven still uncharacterized substance is estimated with the aid of amathematical method in order to assess the suitability thereof as anadditive in photopolymer formulations. A substance is considered to besuitable if its refractive index estimated by the method according tothe invention is ≦1.4600 and its estimated TGA95 value is >100° C.

For assessing the vaporization properties of a component with a smalllayer thickness during a drying process on open surfaces, theconsideration of the volatility of this chemical component is importantand is a measure of the tendency to evaporate. This volatility canpreferably be determined by a thermogravimetric analysis (TGA).

The TGA95 value of the individual components are then determined byweighing an amount of about 10 mg of the sample of the respectivecomponent into an aluminium pan having a volume of 70 μl, introducingthe aluminium pan an oven of a thermobalance, preferably of a TG50thermobalance from Mettler-Toledo, and measuring the loss of mass of thesample in the open aluminium pan at a constant oven heating rate of 20K/min, the starting temperature being 30° C. and the end temperature ofthe oven 600° C., flushing the oven with a 200 ml/min nitrogen streamduring the determination for determining as the TGA 95 value of therespective component, the temperature at which a loss of mass of thesample of 5% by weight, based on the originally weighed in amount of thesample, has occurred.

In order to use the selection method according to the invention, first asubstance to be tested is chosen (step a), a three-dimensional structureof which is created with the aid of a suitable software package. Thisstructure is then subjected to a conformer analysis in a manner knownper se with the aid of a force field method in order to determine theconformers of the substance which have the lowest energy (step b). Thenumber of conformers is then further reduced by further optimization ofthe geometry by a force field method and a subsequent similarityanalysis (step c). Steps a-c can be carried out, for example, with theconformers module of the Materials Studio programme package fromAccelrys.

The conformers generated in steps a-c are then optimized in terms ofgeometry by quantum chemical methods, ideally the B-P86 densityfunctional and a triple C valence basis being used (step d). Theoptimization of the geometry is effected with the use of the continuumsolvation model Conductor like Screening Model (COSMO), theelement-specific COSMO radii optimized by Klamt being used if possible(AIChE Journal, 48, 369, (2002); Fluid Phase Equilibria, 172, 43 (2000);J. Chem. Soc. Perkin Trans. II, 799 (1993)). If elements for which nosuch optimized radii are available are present in the molecule, 1.17times the Bondi valence radius is assumed.

On the basis of the COSMO radii, a cavity outside which the molecule isideally electrostatically shielded from the environment during theoptimization of the geometry is calculated by the quantum chemistrysoftware used. The surface (in Å²) and the volume of this cavity (in Å³)are in each case descriptors in the context of the method according tothe invention (step e).

The third descriptor is derived from the shielding charge surface of thegeometrically optimized molecule, which is obtained in the quantumchemical optimization of the geometry with COSMO. The surface is dividedwith the aid of a suitable computer programme, such as, for example, theCOSMOtherm programme of COSMO/ogic, into segments whose mean shieldingcharge density (σ) is calculated. The third descriptor is then finallyobtained as the second moment (M²) of the frequency distribution (P(σ)),the surface shielding charge densities of these segments (step f):

${M^{2} = {10 \cdot {\sum\limits_{i}\; {{P\left( \sigma_{i} \right)} \cdot \sigma_{i}^{2} \cdot {\Delta\sigma}}}}},$

where Δσ is the interval width with which the discrete frequencydistribution was generated. The charge densities σ are stated in theunit e/nm².

The calculation of the descriptors A, V and M² used in the methodaccording to the invention, carried out in the manner described, iseffected in an identical manner for all conformers taken into account.Subsequently, the individual descriptors of the conformers are averagedaccording to their weight in the Boltzmann distribution (step g). TheBoltzmann factors are determined using the energies which were obtainedas the result of the quantum chemical optimization of the geometry byCOSMO.

Finally with the descriptors determined in this manner, the refractiveindex and the volatility of the substance to be tested are estimated.For this purpose, the molar polarizability (MP) of the compound to betested is first determined with the aid of a QSPR approach known fromthe literature, for example by one of the methods of Crippen et al. (J.Comput. Chem., 7, 565, (1986) or Chem. Inf. Comput. Sci. 39, 868,(1999)). The volatility (TGA95) is estimated according to the inventionon the basis of the QSPR approach (step h):

${{TGA}\; 95} \approx {{207.015 \cdot \frac{M^{2}}{A}} + {41.405 \cdot \sqrt[3]{V}} - 253.2}$

The density is estimated according to the invention according to asecond QSPR approach using (step i):

$\rho = {{0.89 \cdot \frac{M}{V \cdot N_{A}}} - {0.2 \cdot \frac{A}{V}} + {0.01 \cdot \sqrt{M^{2}}}}$

and used to calculate the refractive index at 589 nm (n_(D) ²⁰) with theaid of the Lorentz-Lorenz equation (step j):

$n_{D} = \sqrt{\frac{{2 \cdot \frac{\rho \cdot {MP}}{M}} + 1}{1 - \frac{\rho \cdot {MP}}{M}}}$

In the last step, the suitability of the substance as an additive inphotopolymer formulations is assessed according to the estimatedn²⁰;_(D) and TGA95 value (step k).

Suitable compounds in the context of the method according to theinvention have a refractive index of ≦1.4600 and a TGA95 value of ≧100°C.

Preferred Embodiments

According to a first embodiment, the conformer with the lowest energywhich is found in the conformer analysis, preferably all conformerswhich are up to 4 kJ/mol and particularly preferably all conformerswhich are up to 8 kJ/mol above the lowest conformer, are taken intoaccount for the method.

In a particularly preferred embodiment of the method according to theinvention, a check is carried out in step k) to determine whether thevolatility of the compound to be tested is >120° C. and the refractiveindex n¹⁰;_(D) thereof is ≦1.4500, preferably ≦1.4400, particularlypreferably ≦1.4300.

A further aspect of the invention relates to a photopolymer formulationcomprising matrix polymers, writing monomers and photoinitiators, saidphotopolymer formulation containing at least one plasticizer which isselected by the method according to the invention.

The matrix polymers may be in particular polyurethanes. Preferably, thepolyurethanes are obtained by reacting an isocyanate component a) withan isocyanate-reactive component b).

The isocyanate component a) preferably comprises polyisocyanates.Polyisocyanates which may be used are all compounds well known to theperson skilled in the art or mixtures thereof, which on average have twoor more NCO functions per molecule. These may have an aromatic,araliphatic, aliphatic or cycloaliphatic basis. In minor amounts, it isalso possible concomitantly to use monoisocyanates and/orpolyisocyanates containing unsaturated groups.

For example, butylene diisocyanate, hexamethylene diisocyanate (HDI),isophorone diisocyanate (IPDI),1,8-diisocyanato-4-(isocyanatomethyl)octane, 2,2,4- and/or2,4,4-trimethylhexamethylene diisocyanate, the isomericbis(4,4′-isocyanatocyclohexyl)methanes and mixtures thereof having anydesired isomer content, isocyanatomethyl-1,8-octane diisocyanate,1,4-cyclohexylene diisocyanate, the isomeric cyclohexanedimethylenediisocyanates, 1,4-phenylene diisocyanate, 2,4- and/or 2,6-toluoylenediisocyanate, 1,5-naphthylene diisocyanate, 2,4′- or4,4′-diphenylmethane diisocyanate and/or triphenylmethane4,4′,4″-triisocyanate.

The use of derivatives and monomeric di- or triisocyanates havingurethane, urea, carbodiimide, acylurea, isocyanurate, allophanate,biuret, oxadiazinetrione, uretdione and/or iminooxadiazinedionestructures is likewise possible.

The use of polyisocyanates based on aliphatic and/or cycloaliphatic di-or triisocyanates is preferred.

The polyisocyanates of component a) are particularly preferablydimerized or oligomerized aliphatic and/or cycloaliphatic di- ortriisocyanates.

Isocyanurates, uretdiones and/or iminooxadiazinediones based on HDI,1,8-diisocyanato-4-(isocyanatomethyl)octane or mixtures thereof are veryparticularly preferred.

NCO-functional prepolymers having urethane, allophanate, biuret and/oramide groups can likewise be used as component a). Prepolymers ofcomponent a) are obtained in a manner well known per se to the personskilled in the art by reacting monomeric, oligomeric or polyisocyanatesa1) with isocyanate-reactive compounds a2) in suitable stoichiometrywith optional use of catalysts and solvents.

Suitable polyisocyanates a1) are all aliphatic, cycloaliphatic, aromaticor araliphatic di- and triisocyanates know per se to the person skilledin the art, it being unimportant whether these were obtained by means ofphosgenation or by phosgene-free processes. In addition, the highermolecular weight secondary products of monomeric di- and/ortriisocyanates having a urethane, urea, carbodiimide, acylurea,isocyanurate, allophanate, biuret, oxadiazinetrione, uretdione oriminooxadiazinedione structure, which are known per se to the personskilled in the art, can also be used, in each case individually or asany desired mixtures with one another.

Examples of suitable monomeric di- or triisocyanates which can be usedas component a1) are butylene diisocyanate, hexamethylene diisocyanate(IMO, isophorone diisocyanate (IPDI), trimethylhexamethylenediisocyanate (TMDI), 1,8-diisocyanato-4-(isocyanatomethyl)octane,isocyanatomethyl-1,8-octane diisocyanate (TIN), 2,4- and/or 2,6-toluenediisocyanate.

OH-functional compounds are preferably used as isocyanate-reactivecompounds a2) for the synthesis of the prepolymers. These are analogousto the OH-functional compounds as described below for the component b).

The use of amines for the prepolymer preparation is also possible. Forexample, ethylenediamine, diethylenetriamine, triethylenetetramine,propylenediamine, diaminocyclohexane, diaminobenzene, diaminobisphenyl,difunctional polyamines, such as, for example, Jeffamine®,amine-terminated polymers having number average molar masses of up to 10000 g/mol or any desired mixtures thereof with one another are suitable.

For the preparation of prepolymers containing biuret groups, isocyanateis reacted in excess with amine, a biuret group forming. Suitable aminesin this case for the reaction with the di-, tri- and polyisocyanatesmentioned are all oligomeric or polymeric, primary or secondary,difunctional amines of the abovementioned type.

Preferred prepolymers are urethanes, allophanates or biurets ofaliphatic isocyanate-functional compounds and oligomeric or polymericisocyanate-reactive compounds having number average molar masses of 200to 10 000 g/mol; urethanes, allophanates or biurets of aliphaticisocyanate-functional compounds and oligomeric or polymeric polyols orpolyamines having number average molar masses of 500 to 8500 g/mol areparticularly preferred and allophanates of HDI or TMDI and difunctionalpolyetherpolyols having number average molar masses of 1000 to 8200g/mol are very particularly preferred.

The prepolymers described above preferably have residual contents offree monomeric isocyanate of less than 1% by weight, particularlypreferably less than 0.5% by weight, very particularly preferably lessthan 0.2% by weight.

Of course, the isocyanate component may contain further isocyanatecomponents proportionately in addition to the prepolymers described.Aromatic, araliphatic, aliphatic and cycloaliphatic di-, tri- orpolyisocyanates are suitable for this purpose. It is also possible touse mixtures of said di-, tri- or polyisocyanates. Examples of suitabledi-, tri- or polyisocyanates are butylene diisocyanate, hexamethylenediisocyanate (HDI), isophorone diisocyanate (IPDI),1,8-diisocyanato-4-(isocyanatomethyl)octane, 2,2,4- and/or2,4,4-trimethylhexamethy lene diisocyanate (TMDI), the isomericbis(4,4′-isocyanatocyclo-hexyl)methanes and mixtures thereof having anydesired isomer content, isocyanatomethyl 1,8-octane diisocyanate,1,4-cyclohexylene diisocyanate, the isomeric cyclohexanedimethylenediisocyanates, 1,4-phenylene diisocyanate, 2,4- and/or 2,6-toluoylenediisocyanate, 1,5-naphthylene diisocyanate, 2,4′- or4,4′-diphenylmethane diisocyanate, triphenylmethane4,4′,4″-triisocyanate or derivatives thereof having a urethane, urea,carbodiimide, acylurea, isocyanurate, allophanate, biuret,oxadiazinetrione, uretdione, iminooxadiazinedione structure and mixturesthereof. Polyisocyanates based on oligomerized and/or derivatizeddiisocyanates which were freed from excess diisocyanate by suitablemethods, in particular those of hexamethylene diisocyanate, arepreferred. The oligomeric isocyanurates, uretdiones andiminooxadiazinediones of HDI and mixtures thereof are particularlypreferred.

It is optionally also possible for the isocyanate component a)proportionately to contain isocyanates which are partly reacted withisocyanate-reactive ethylenically unsaturated compounds. α,β-Unsaturatedcarboxylic acid derivatives, such as acrylates, methacrylates, maleates,fumarates, maleimides, acrylamides, and vinyl ethers, propenyl ethers,allyl ethers and compounds which contain dicyclopentadienyl units andhave at least one group reactive towards isocyanates are preferably usedhere as isocyanate-reactive ethylenically unsaturated compounds; theseare particularly preferably acrylates and methacrylates having at leastone isocyanate-reactive group. Suitable hydroxy-functional acrylates ormethacrylates are, for example, compounds such as2-hydroxyethyl(meth)acrylate, polyethylene oxide mono(meth)acrylates,polypropylene oxide mono(meth)acrylates, polyalkylene oxidemono(meth)acrylates, poly(ε-caprolactone)mono(meth)acrylates, such as,for example, Tone® M100 (Dow, USA), 2-hydroxypropyl(meth)acrylate,4-hydroxybutyl(meth)acrylate,3-hydroxy-2,2-dimethylpropyl(meth)acrylate, the hydroxy-functionalmono-, di- or tetra(meth)acrylates of polyhydric alcohols, such astrimethylolpropane, glycerol, pentaerythritol, dipentaerythritol,ethoxylated, propoxylated or alkoxylated trimethylolpropane, glycerol,pentaerythritol, dipentaerythritol or the industrial mixtures thereof.In addition, isocyanate-reactive oligomeric or polymeric unsaturatedcompounds containing acrylate and/or methacrylate groups are suitablealone or in combination with the abovementioned monomeric compounds. Theproportion of isocyanates which are partly reacted withisocyanate-reactive ethylenically unsaturated compounds, based on theisocyanate component a) is 0 to 99%, preferably 0 to 50%, particularlypreferably 0 to 25% and very particularly preferably 0 to 15%.

It is optionally also possible for the abovementioned isocyanatecomponent a) completely or proportionately to contain isocyanates, whichare completely or partly reacted with blocking agents known to theperson skilled in the art from coating technology. The following may bementioned as an example of blocking agents: alcohols, lactams, oximes,malonic esters, alkyl acetoacetates, triazoles, phenols, imidazoles,pyrazoles and amines, such as, for example, butanone oxime,diisopropylamine, 1,2,4-triazole, dimethyl-1,2,4-triazole, imidazole,diethyl malonate, ethyl acetoacetate, acetone oxime,3,5-dimethylpyrazole, ε-caprolactam, N-tert-butylbenzylamine,cyclopentanone carboxyethyl ester or any desired mixtures of theseblocking agents.

All polyfunctional, isocyanate-reactive compounds which have on averageat least 1.5 isocyanate-reactive groups per molecule can in principle beused as component b).

Isocyanate-reactive groups in the context of the present invention arepreferably hydroxy, amino or thio groups; hydroxy compounds areparticularly preferred.

Suitable polyfunctional, isocyanate-reactive compounds are, for example,polyester-, polyether-, polycarbonate-, poly(meth)acrylate- and/orpolyurethanepolyols.

Suitable polyesterpolyols are, for example, linear polyesterdiols orbranched polyester polyols, as are obtained in a known manner fromaliphatic, cycloaliphatic or aromatic di- or polycarboxylic acids ortheir anhydrides with polyhydric alcohols having an OH functionality of≧2.

Examples of such di- or polycarboxylic acids or anhydrides are succinic,glutaric, adipic, pimelic, suberic, azelaic, sebaccic,nonanedicarboxylic, decanedicarboxylic, terephthalic, isophthalic,o-phthalic, tetrahydrophthalic, hexahydrophthalic or trimellitic acidand acid anhydrides such as o-phthalic, trimellitic or succinicanhydride, or any desired mixtures thereof with one another.

Examples of such suitable alcohols are ethanediol, di-, tri- andtetraethylene glycol, 1,2-propanediol, di-, tri- and tetrapropyleneglycol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 2,3-butanediol,1,5-pentanediol, 1,6-hexanediol, 2,2-dimethyl-1,3-propanediol,1,4-dihydroxycyclohexane, 1,4-dimethylolcyclohexane, 1,8-octanediol,1,10-decanediol, 1,12-dodecanediol, trimethylolpropane, glycerol or anydesired mixtures thereof with one another.

The polyesterpolyols may also be based on natural or raw materials, suchas castor oil. It is also possible for the polyesterpolyols to be basedon homo- or copolymers of lactones, as can preferably be obtained by anaddition reaction of lactones or lactone mixtures, such asbutyrolactone, ε-caprolactone and/or methyl-ε-caprolactone, withhydroxy-functional compounds, such as polyhydric alcohols having an OHfunctionality of ≧2, for example of the abovementioned type.

Such polyesterpolyols preferably have number average molar masses of 400to 4000 g/mol, particularly preferably of 500 to 2000 g/mol. Their OHfunctionality is preferably 1.5 to 3.5, particularly preferably 1.8 to3.0.

Suitable polycarbonatepolyols are obtainable in a manner known per se byreacting organic carbonates or phosgene with diols or diol mixtures.

Suitable organic carbonates are dimethyl, diethyl and diphenylcarbonate.

Suitable diols or mixtures comprise the polyhydric alcohols mentionedper se in connection with the polyester segments and having an OHfunctionality of ≧2, preferably 1,4-butanediol, 1,6-hexanediol and/or3-methylpentanediol, or polyesterpolyols can be converted intopolycarbonatepolyols.

Such polycarbonatepolyols preferably have number average molar masses of400 to 4000 g/mol, particularly preferably of 500 to 2000 g/mol. The OHfunctionality of these polyols is preferably 1.8 to 3.2, particularlypreferably 1.9 to 3.0.

Suitable polyetherpolyols are polyadducts of cyclic ethers with OH- orNH-functional starter molecules, said polyadducts optionally having ablock structure.

Suitable cyclic ethers are, for example, styrene oxides, ethylene oxide,propylene oxide, tetrahydrofuran, butylene oxide, epichlorohydrin andany desired mixtures thereof.

Starters which may be used are the polyhydric alcohols mentioned per sein connection with the polyesterpolyols and having an OH functionalityof ≧2 and primary or secondary amines and amino alcohols.

Preferred polyetherpolyols are those of the abovementioned type,exclusively based on propylene oxide, or random or block copolymersbased on propylene oxide with further 1-alkylene oxides, the proportionof the 1-alkylene oxide not being higher than 80% by weight. Inaddition, poly(trimethylene oxides) and mixtures of the polyolsmentioned as being preferred are preferred. Propylene oxide homopolymersand random or block copolymers which have oxyethylene, oxypropyleneand/or oxybutylene units are particularly preferred, the proportion ofoxypropylene units, based on the total amount of all oxyethylene,oxypropylene and oxybutylene units, accounting for at least 20% byweight, preferably at least 45% by weight. Here, oxypropylene andoxybutylene comprise all respective linear and branched C3- andC4-isomers.

Such polyetherpolyols preferably have number average molar masses of 250to 10 000 g/mol, particularly preferably of 500 to 8500 g/mol and veryparticularly preferably of 600 to 4500 g/mol. The OH functionality ispreferably 1.5 to 4.0, particularly preferably 1.8 to 3.1.

In addition, aliphatic, araliphatic or cycloaliphatic di-, tri- orpolyfunctional alcohols which have a low molecular weight, i.e. havingmolecular weights of less than 500 g/mol, and a short chain, i.e.containing 2 to 20 carbon atoms, are also suitable as polyfunctional,isocyanate-reactive compounds as constituents of component c).

These may be, for example, ethylene glycol, diethylene glycol,triethylene glycol, tetraethylene glycol, dipropylene glycol,tripropylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol,neopentylglycol, 2-ethyl-2-butylpropanediol, trimethylpentanediol,positional isomers of diethyloctanediol, 1,3-butylene glycol,cyclohexanediol, 1,4-cyclohexanedimethanol, 1,6-hexanediol, 1,2- and1,4-cyclohexanediol, hydrogenated bisphenol A(2,2-bis(4-hydroxycyclohexyl)propane), 2,2-dimethyl-3-hydroxy-propionicacid (2,2-dimethyl-3-hydroxypropyl ester). Examples of suitable triolsare trimethylolethane, trimethylolpropane or glycerol. Suitablehigher-functional alcohols are ditrimethylolpropane, pentaerythritol,dipentaerythritol or sorbitol.

One or more photoinitiators are used as component c). These are usuallyinitiators which can be activated by actinic radiation and initiate apolymerization of the corresponding polymerizable groups.Photoinitiators are commercially distributed compounds known per se, adistinction being made between monomolecular (type I) and bimolecular(type II) initiators. Furthermore, these initiators are used for freeradical, anionic (or), cationic (or mixed) forms of the abovementionedpolymerizations, depending on the chemical nature.

(Type I) systems for the free radical photopolymerization are, forexample, aromatic ketone compounds, e.g. benzophenones, in combinationwith tertiary amines, alkylbenzophenones,4,4′-bis(dimethylamino)benzophenone (Michlers ketone), anthrone andhalogenated benzophenones or mixtures of said types. (Type II)initiators, such as, benzoin and its derivatives, benzil ketals,acylphosphine oxides, e.g. 2,4,6-trimethylbenzoyl-diphenylphosphineoxide, bisacylophosphine oxides, phenylglyoxylic esters, campherquinone,alpha-aminoalkylphenones, alpha-,alpha-dialkoxyacetophenones,1-[4-(phenylthio)phenyl]octane-1,2-dione 2-(O-benzoy loxime),differently substituted hexarylbisimidazoles (HABI) with suitablecoinitiators, such as, for example, mercaptobenzoxazole andalpha-hydroxyalkylphenones are furthermore suitable. The photoinitiatorsystems described in EP-A 0223587 and consisting of a mixture of anammonium aryl borate and one or more dyes can also be used as aphotoinitiator. For example, tetrabutylammonium triphenylhexylborate,tetrabutylammonium triphenylbutylborate, tetrabutylammoniumtrinaphthylbutylborate, tetramethylammonium triphenylbenzylborate,tetra(n-hexyl)ammonium (sec-butyl)triphenylborate,1-methyl-3-octylimidazolium dipentyldiphenylborate, tetrabutylammoniumtris(4-tert-butyl)phenyl-butylborate, tetrabutylammoniumtris(3-fluorophenyl)hexylborate and tetrabutylammoniumtris(3-chloro-4-methylphenyl)hexylborate are suitable as the ammoniumaryl borate. Suitable dyes are, for example, new methylene blue,thionine, basic yellow, pinacynol chloride, rhodamine 6G, gallocyanine,ethylviolet, Victoria blue R, celestine blue, quinaldine red, crystalviolet, brilliant green, astrazone orange G, darrow red, pyronine Y,basic red 29, pyrillium I, safranine O, cyanine and methylene blue,azure A (Cunningham et al., RadTech'98 North America UV/EB ConferenceProceedings, Chicago, Apr. 19-22, 1998).

The photoinitiators used for the anionic polymerization are as a rule(type I) systems and are derived from transition metal complexes of thefirst series. Here are chromium salts, such as, for example,trans-Cr(NH₃)₂(NCS)₄— (Kutal et al, Macromolecules 1991, 24, 6872) orferrocenyl compounds (Yamaguchi et al., Macromolecules 2000, 33, 1152).A further possibility of anionic polymerization consists in the use ofdyes, such as crystal violet leuconitrile or malchite greenleuconitrile, which can polymerize cyanoacrylates by photolyticdecomposition (Neckers et al., Macromolecules 2000, 33, 7761). However,the chromophore is incorporated thereby into the polymer so that theresulting polymers are coloured throughout.

The photoinitiators used for the cationic polymerization substantiallycomprise three classes: aryldiazonium salts, onium salts (herespecifically: iodonium, sulphonium and selenonium salts) andorganometallic compounds. On irradiation both in the presence and in theabsence of a hydrogen donor, phenyldiazonium salts can produced a cationthat initiates the polymerization. The efficiency of the overall systemis determined by the nature of the counterion used for the diazoniumcompound. The not very reactive but very expensive SbF₆ ⁻, AsF₆ ⁻ or PF₆are preferred here. These compounds are as a rule not very suitable foruse in coating of the thin films since the nitrogen liberated after theexposure reduces the surface quality (pinholes) (Li et al., PolymericMaterials Science and Engineering, 2001, 84, 139). Very widely used andcommercially available in many forms are onium salts, especiallysulphonium and iodonium salts. The photochemistry of these compounds hasbeen investigated for a long time. After excitation, the iodonium saltsinitially decompose homolytically and thus produce a free radical and aradical anion which is stabilized by H abstraction and releases a protonand then initiates the cationic polymerization (Dektar et al. J. Org.Chem. 1990, 55, 639; J. Org. Chem., 1991, 56, 1838). This mechanismpermits the use of iodonium salts also for free radicalphotopolymerization. The choice of the counterion is once again ofconsiderable importance here; SbF₆ ⁻, AsF₆ ⁻ or PF₆ are likewisepreferred. Otherwise, this choice of the substitution of the aromatic iscompletely free in this structure class and is determined substantiallyby the availability of suitable starting building blocks for thesynthesis. The sulphonium salts are compounds which decompose inaccording to Norrish(II) (Crivello et al., Macromolecules, 2000, 33,825). In the case of the sulphonium salts, too, the choice of thecounterion is of critical importance and manifests itself substantiallyin the curing rate of the polymers. The best results are as a ruleobtained with SbF₆ ⁻ salts. Since the self-absorption of iodonium andsulphonium salts is at <300 nm, these compounds must be appropriatelysensitized for the photopolymerization with near UV or short-wavevisible light. This is effected by the use of more highly absorbingaromatics such as, for example, anthracene and derivatives (Gu et al.,Am. Chem. Soc. Polymer Preprints, 2000, 41 (2), 1266) or phenothiazineor derivatives thereof (Hua et al, Macromolecules 2001, 34, 2488-2494).

It may also be advantageous to use mixtures of these compounds.Depending on the radiation source used for the curing, type andconcentration of photoinitiator must be adapted in a manner known to aperson skilled in the art. Further details are described, for example,in P. K. T. Oldring (Ed.), Chemistry & Technology of UV & EBFormulations For Coatings, Inks & Paints, Vol. 3, 1991, SITA Technology,London, pages 61-328.

Preferred photoinitiators c) are mixtures of tetrabutylammoniumtriphenylhexylborate, tetrabutylammonium triphenylbutylborate,tetrabutylammonium trinaphthylbutylborate, tetrabutylammoniumtris-(4-tert-butyl)phenylbutylborate, tetrabutylammoniumtris-(3-fluorophenyl)hexylborate and tetrabutylammoniumtris-(3-chloro-4-methylphenyl)hexyl-borate with dyes, such as, forexample, astrazone orange G, methylene blue, new methylene blue, azureA, pyrillium I, safranine O, cyanine, gallocyanine, brilliant green,crystal violet, ethyl violet and thionine.

The photopolymer formulation may additionally contain urethanes asplasticizers, it being possible for the urethanes preferably to besubstituted by at least one fluorine atom.

The urethanes are preferably compounds which have a structural elementof the general formula I.

They can be obtained from monofunctional alcohols and monofunctionalisocyanates. These are preferably substituted by at least one fluorineatom.

It is more preferable if the fluorourethanes have the general formula II

in which n is >1 and n is <8 and R¹, R², R³ are hydrogen and/or,independently of one another, linear, branched, cyclic or heterocyclicorganic radicals which are unsubstituted or optionally also substitutedby heteroatoms, at least one of the radicals R¹, R², R³ beingsubstituted by at least one fluorine atom. Here, R¹ is particularlypreferably an organic radical having at least one fluorine atom.

According to a further embodiment, R¹ may comprise 1-20 CF₂ groupsand/or one or more CF₃ groups, particularly preferably 1-15 CF₂ groupsand/or one or more CF₃ groups, particularly preferably 1-10 CF₂ groupsand/or one or more CF₃ groups, very particularly preferably 1-8 CF₂groups and/or one or more CF₃ groups, R² may comprise a C1-C20 alkylradical, preferably a C1-C15 alkyl radical, particularly preferably aC1-C10 alkyl radical or hydrogen, and/or R³ may comprise a C1-C20 alkylradical, preferably a C1-C15 alkyl radical, particularly preferably aC1-C10 alkyl radical or hydrogen.

The fluorourethanes may have a fluorine content of 10-80% by weight offluorine, preferably of 13-70% by weight of fluorine and particularlypreferably 17.5-65% by weight of fluorine.

According to a further preferred embodiment of the invention, it isenvisaged that the photopolymer formulation contains 10 to 89.999% byweight, preferably 25 to 70% by weight, of matrix polymers, 10 to 60% byweight, preferably 25 to 50% by weight, of writing monomers, 0.001 to 5%by weight of photoinitiators and optionally 0 to 4% by weight,preferably 0 to 2% by weight, of catalyst, 0 to 5% by weight, preferably0.001 to 1% by weight, of free radical stabilizers, 0 to 30% by weight,preferably 0 to 25% by weight, of plasticizers and 0 to 5% by weight,preferably 0.1 to 5% by weight, of further additives, the sum of allconstituents being 100% by weight.

Photopolymer formulations having 25 to 70% by weight of matrix polymersconsisting of compounds of component a) and of component b), 25 to 50%by weight of writing monomers, 0.001 to 5% by weight of photoinitiators,0 to 2% by weight of catalyst, 0.001 to 1% by weight of free radicalstabilizers, optionally 0 to 25% by weight of the urethanes describedabove and optionally 0.1 to 5% by weight of further additives areparticularly preferably used.

A further preferred embodiment of the invention envisages that thephotopolymer formulation contains urethanes having a number averagemolecular weight of ≦250 g/mol, preferably of ≦200 g/mol andparticularly preferably of ≦190 g/mol.

The photopolymer formulation therefore advantageously contains aliphaticurethanes. In this case, the aliphatic urethanes may have in particularthe general formula (III)

in which R⁴, R⁵, R⁶, independently of one another, are linear orbranched (C1-C20)-alkyl radicals optionally substituted by heteroatoms.It is particularly preferable if R⁴ is a linear or branched(C1-C8)-alkyl radical, R⁵ is a linear or branched (C1-C8)-alkyl radicaland/or R⁶ is a linear or branched (C1-C8)-alkyl radical, it beingparticularly preferable if R⁴ is a linear or branched (C1-C4)-alkylradical and R⁵ is a linear or branched (C1-C6)-alkyl radical and R⁶ ishydrogen. In this case, it was in fact found that the urethanes thusobtained are very compatible with the polyurethane matrix and show theeffect described here.

According to a further preferred embodiment, it is envisaged that theurethanes have substantially no free NCO groups.

The writing monomers can preferably comprise a monofunctional acrylateof the general formula (IV)

in which R⁷, R⁸ are hydrogen and/or, independently of one another,linear, branched, cyclic or heterocyclic unsubstituted organic radicals.

It is also possible for the writing monomers to comprise apolyfunctional writing monomer, it being possible for this to be inparticular a polyfunctional acrylate.

The polyfunctional acrylate can preferably have the general formula (V)

in which n is ≧2 and n is ≦4 and R⁹, R¹⁰ are hydrogen and/Or,independently of one another, linear, branched, cyclic or heterocyclicorganic radicals which are unsubstituted or optionally also substitutedby heteroatoms.

The present invention furthermore relates to the use of a photopolymerformulation according to the invention for the production of holographicmedia, in particular for the production of in-line holograms, off-axisholograms, full-aperture transfer holograms, white light transmissionholograms, Denisyuk holograms, off-axis reflection holograms, edge-litholograms and holographic stereograms.

EXAMPLES

The invention is explained in more detail below with reference toexamples. First, the synthesis and characterization of the examplemolecules are described and thereafter the handling thereof in themethod according to the invention.

Unless noted otherwise, all stated percentages relate to percent byweight.

Determination of the Refractive Index

Measurement of the refractive index n²⁰;_(D) at a wavelength of 589 nm:a sample of the example compound was introduced into an Abberefractometer and n²⁰;_(D) was measured.

Determination of the Vapour Pressure

For Examples 2 and 7, the synthesis of which is described further below,the vapour pressures were determined under a nitrogen atmosphere in acirculation apparatus (isobar in an Ebulliometer) by the Röck methodaccording to the OECD guideline for the testing of chemicals, No. 104.The resulting vapour pressure curves are shown in FIG. 5 in thetemperature range from 90 to 180° C. The resulting parameters of theAntoine equation

${\lg \frac{P^{Sat}}{hPa}} = {A - \frac{B}{C + {T\left( {{^\circ}\mspace{14mu} {C.}} \right)}}}$

are accordingly:

TABLE 1 Physical data of Examples 2 and 7 Vapour Vapour Parameters ofthe pressure pressure TGA Antoine equation at 80° C. at 100° C. 95Example A B C [hPa] [hPa] [° C.] 2 15.6189 2616.075 90.3596 1.30 7.3072.5 7 6.5466 1053.404 42.458 0.13 0.42 111.8

It is evident from this that the equilibrium vapour pressure, forexample for a temperature of 100° C. in both Examples 2 and 7, is <10hPa, so that it would be expected that the two components havesufficient stability in the formulation. The TGA95 values of the two twoExamples 2 and 7 on the other hand correlate substantially better withthe observed behaviour during the film coating.

FIG. 1 shows the measured vapour pressure curves of Examples 2 and 7.

Determination of the TGA95 Value

The TGA95 values of the individual components are determined by weighingan amount of about 10 mg of the respective component into an aluminiumpan having a volume of 70 introducing the aluminium pan into an oven ofa thermobalance, preferably a TG50 thermobalance from Mettler-Toledo,and measuring the loss of mass (of the sample) in the open aluminium panat a constant oven heating rate of 20 K/min, the starting temperaturebeing 30° C. and the end temperature of the oven being 600° C., the ovenbeing flushed with a 200 ml/min nitrogen stream during the determinationand the temperature at which a loss of mass of the sample of 5% byweight, based on the originally weighed in amount of the sample, hasoccurred being determined as the TGA95 value of the respectivecomponent.

Measurement of the Holographic Properties DE and Δn of the HolographicMedia by Means of Two-Beam Interference in Reflection Arrangement

For the measurement of the holographic performance, the protective foilof the holographic film is peeled off and the holographic film islaminated on the photopolymer side with a 1 mm thick glass plate ofsuitable length and width using a rubber roller with gentle pressure.This sandwich of glass and photopolymer film can now be used fordetermining the holographic performance parameters DE and Δn.

The holographic media produced as described below were then tested withregard to the holographic properties by means of a measurementarrangement according to FIG. 3, as follows:

The beam of an He—Ne laser (emission wavelength 633 nm) was convertedwith the aid of the spatial filter (SF) and together with thecollimation lens (CL) into a parallel homogeneous beam. The final crosssections of the signal and reference beam are established by the irisdiaphragm (I). The diameter of the iris diaphragm opening is 0.4 cm. Thepolarization-dependent beam splitters (PBS) split the laser beam intotwo coherent equally polarized beams. Via the λ/2 plates, the power ofthe reference beam was adjusted to 0.5 mW and the power of the signalbeam to 0.65 mW. The powers were determined using the semiconductordetectors (D) with sample removed. The angle of incidence (α₀) of thereference beam is −21.8° and the angle of incidence (β₀) of the signalbeam is 41.8°. The angles are measured starting from the sample normalto the beam direction. According to FIG. 3, α₀ therefore has a negativesign and β₀ a positive sign. At the location of the sample (medium), theinterference field of the two overlapping beams produced a grating oflighter and darker strips which are perpendicular to the angledissectors of the two beams incident on the sample (reflectionhologram). The strip spacing Λ, also referred to as grating period, inthe medium is ˜225 nm (the refractive index of the medium is seen to be˜1.504).

FIG. 3 shows the holographic experimental setup with which thediffraction efficiency (DE) of the media was measured.

Holograms were recorded in the medium in the following manner:

-   -   both shutters (S) are opened for the exposure time t.    -   thereafter, with closed shutters (S), the medium was allowed a        time of 5 minutes for diffusion of the still unpolymerized        writing monomers.

The holograms recorded were now read in the following manner. Theshutter of the signal beam remained closed. The shutter of the referencebeam was opened. The iris diaphragm of the reference beam was closed toa diameter of <1 mm. This ensured that the beam was always completely inthe previously recorded hologram for all angles of rotation (Ω) of themedium. The turntable, now computer controlled, covered the angle rangefrom Ω_(min) to Ω_(max) with an angle step width of 0.05°. Ω is measuredfrom the sample normal to the reference direction of the turntable. Thereference direction of the turntable is obtained when the angle ofincidence of the reference beam and that of the signal beam have thesame absolute value during recording of the hologram, i.e. α₀=−31.8° andβ₀=31.8°. Ω_(recording) is then 0°. For α₀=−21.8° and β₀=41.8°,Ω_(recording) is therefore 10°. In general, the following is true forthe interference field during recording of the hologram:

α₀θ₀+Ω_(recording).

θ₀ is the semiangle on the laboratory system outside the medium and thefollowing is true during recording of the hologram:

$\theta_{0} = {\frac{\alpha_{0} - \beta_{0}}{2}.}$

In this case, θ₀ is therefore −31.8°. At each angle of rotation Ωapproached, the powers of the beam transmitted in the zeroth order weremeasured by means of the corresponding detector D and the powers of thebeam diffracted in the first order were measured by means of thedetector D. The diffraction efficiency was obtained at each angle Ωapproached as a quotient of:

$\eta = \frac{P_{D}}{P_{D} + P_{T}}$

P_(D) is the power in the detector of the diffracted beam and P_(T) isthe power in the detector of the transmitted beam.

By means of the method described above, the Bragg curve (it describesthe diffraction efficiency η as a function of the angle of rotation Ω ofthe recorded hologram) was measured and was stored in a computer. Inaddition, the intensity transmitted in the zeroth order was plottedagainst the angle of rotation Ω and stored in a computer.

The maximum diffraction efficiency (DE=η_(max)) of the hologram, i.e.its peak value, was determined at Ω_(reconstruction). It may have beennecessary for this purpose to change the position of the detector of thediffracted beam in order to determine this maximum value.

The refractive index Δn and the thickness d of the photopolymer layerwas now determined by means of the coupled wave theory (cf. H. Kogelnik,The Bell System Technical Journal, Volume 48, November 1969, Number 9,page 2909-page 2947) from the measured Bragg curve and variation of thetransmitted intensity as a function of angle. It should be noted that,owing to the thickness shrinkage occurring as result of thephotopolymerization, the strip spacing Λ′ of the hologram and theorientation of the strips (slant) may differ from the strip spacing Λ ofthe interference pattern and the orientation thereof. Accordingly, theangle α₀′ and the corresponding angle of the turntableΩ_(reconstruction), at which maximum diffraction efficiency is reachedwill also differ from α₀ and from the corresponding Ω_(recording),respectively. The Bragg condition changes as a result. This change istaken into account in the evaluation method. The evaluation method isdescribed below:

All geometrical quantities which relate to the recorded hologram and notto the interference pattern are shown as quantities represented by adashed line.

According to Kogelnik, the following is true for the Bragg curve η(Ω) ofreflection hologram:

$\eta = \left\{ \begin{matrix}{\frac{1}{1 - \frac{1 - \left( {\xi/v} \right)^{2}}{\sin^{2}\left( \sqrt{\xi^{2} - v^{2}} \right)}},{{{{for}\mspace{14mu} v^{2}} - \xi^{2}} < 0}} \\{\frac{1}{1 + \frac{1 - \left( {\xi/v} \right)^{2}}{\sinh^{2}\left( \sqrt{v^{2} - \xi^{2}} \right)}},{{{{for}\mspace{14mu} v^{2}} - \xi^{2}} \geq 0}}\end{matrix} \right.$

with:

$v = \frac{{\pi \cdot \Delta}\; {n \cdot d^{\prime}}}{\lambda \cdot \sqrt{{c_{s} \cdot c_{r}}}}$$\xi = {{- \frac{d^{\prime}}{2 \cdot c_{s}}} \cdot {DP}}$$c_{s} = {{\cos \left( \vartheta^{\prime} \right)} - {{\cos \left( \psi^{\prime} \right)} \cdot \frac{\lambda}{n \cdot \Lambda^{\prime}}}}$c_(r) = cos (ϑ^(′))${DP} = {\frac{\pi}{\Lambda^{\prime}} \cdot \left( {{2 \cdot {\cos \left( {\psi^{\prime} - \vartheta^{\prime}} \right)}} - \frac{\lambda}{n \cdot \Lambda^{\prime}}} \right)}$$\psi^{\prime} = \frac{\beta^{\prime} + \alpha^{\prime}}{2}$$\Lambda^{\prime} = \frac{\lambda}{2 \cdot n \cdot {\cos \left( {\psi^{\prime} - \alpha^{\prime}} \right)}}$

On reading the hologram (“reconstruction”), the following is true, asshown analogously above:

∂′₀=θ₀+Ω

sin(∂′₀)=n·sin(∂′)

Under the Bragg condition, the “dephasing” DP is 0. Accordingly, thefollowing is true:

α′₀=θ₀+Ω_(reconstruction)

sin(α′₀)=n·sin(α′)

The still unknown angle β′ can be determined from the comparison of theBragg condition of the interference field on recording of the hologramand the Bragg condition on reading the hologram, assuming that onlythickness shrinkage takes place. Then follows:

${\sin \left( \beta^{\prime} \right)} = {\frac{1}{n} \cdot \left\lbrack {{\sin \left( \alpha_{0} \right)} + {\sin \left( \beta_{0} \right)} - {\sin \left( {\theta_{0} + \Omega_{reconstruction}} \right)}} \right\rbrack}$

v is the grating thickness, ξ is the detuning parameter and ψ′ is theorientation (slant) of the refractive index grating which was recorded.α′ and β′ correspond to the angles α₀ and β₀ of the interference fieldon recording of the hologram, but measured in the medium and applicableto the grating of the hologram (after thickness shrinkage). n is themean refractive index of the photopolymer and was set at 1.504. λ is thewavelength of the laser light in vacuo.

The maximum diffraction efficiency (DE=η_(max)) is then obtained for ξ=0as:

${DE} = {{\tanh^{2}(v)} = {\tanh^{2}\left( \frac{{\pi \cdot \Delta}\; {n \cdot d^{\prime}}}{\lambda \cdot \sqrt{{\cos \left( \alpha^{\prime} \right)} \cdot {\cos \left( {\alpha^{\prime} - {2\psi}} \right)}}} \right)}}$

The measured data of the diffraction efficiency, the theoretical Braggcurve and the transmitted intensity are, as shown in FIG. 4, plottedagainst the centred angle of rotation ΔΩ≡Ω_(reconstruction)−Ω=α′₀−∂′₀,also referred to as angle detuning.

Since DE is known, the shape of the theoretical Bragg curve according toKogelnik is determined only by the thickness d′ of the photopolymerlayer. Δn is subsequently corrected via DE for a given thickness d′ sothat measurement and theory of DE always agree. d′ is now adapted untilthe angle positions of the first secondary minima of the theoreticalBragg curve agree with the angle positions of the first secondary maximaof the transmitted intensity and additionally the full width at halfmaximum (FWHM) for the theoretical Bragg curve and the transmittedintensity agree.

Since the direction in which a reflection hologram concomitantly rotateson reconstruction by means of an Ω scan, but the detector for thediffracted light can detect only a finite angle range, the Bragg curveof broad holograms (small d′) is not completely detected in an Ω scan,but only the central region, with suitable detector positioning. Thatshape of the transmitted intensity which is complementary to the Braggcurve is therefore additionally used for adapting the layer thicknessd′.

FIG. 4 shows the plot of the Bragg curve η according to the coupled wavetheory (dashed line), of the measured diffraction efficiency (solidcircles) and of the transmitted power (black solid line) against theangle detuning ΔΩ.

For a formulation, this procedure was possibly repeated several timesfor different exposure times t on different media in order to determinethe average energy dose of the incident laser beam at which DE reachesthe saturation value during recording of the hologram. The averageenergy dose E is obtained from the powers of the two part-beamscoordinated with the angles α₀ and β₀ (reference beam with P_(r)=0.50 mWand signal beam with P_(s)=0.63 mW), the exposure time t and thediameter of the iris diaphragm (0.4 cm), as follows:

${E\left( {{mJ}/{cm}^{2}} \right)} = \frac{2 \cdot \left\lbrack {P_{r} + P_{s}} \right\rbrack \cdot {t(s)}}{{\pi \cdot 0.4^{2}}{cm}^{2}}$

The powers of the part-beams were adapted so that the same power densityis achieved in the medium at the angles α₀ and β₀ used.

In examples, respectively the maximum value in Δn is reported, and thedoses used are between 4 and 64 ml/cm² per arm.

Substances Used

CGI-909 (tetrabutylammonium tris(3-chloro-4-methylphenyl)(hexyl)borate,[1147315-11-4]) is an experimental product produced by CIBA Inc., Basle,Switzerland.

The (fluorinated) alcohols and monofunctional isocyanates used wereobtained in the chemicals trade.

1,8-Diisocyanato-4-(isocyanatomethyl)octane (TIN) was prepared asdescribed in EP 749958.

2,4,4-Trimethylhexane 1,6-diisocyanate, Vestanat TMDI, is a product ofEvonik Degussa GmbH, Marl, Germany.

Preparation of the Polyol Component:

In a 11 flask, 0.18 g of tin octoate, 374.8 g of ε-caprolactone and374.8 g of a difunctional polytetrahydrofuranpolyetherpolyol (equivalentweight 500 g/mol OH) were initially introduced and heated to 120° C. andkept at this temperature until the solids content (proportion ofnonvolatile constituents) was 99.5% by weight or more. Thereafter,cooling was effected and the product was obtained as a waxy solid.

Preparation of Urethane Acrylate 1:phosphorothioyltris(oxybenzene-4,1-diylcarbamoyloxyethane-2,1-diyl)trisacrylate

In a 500 ml round-bottomed flask, 0.1 g of2,6-di-tert-butyl-4-methylphenol, 0.05 g of dibutyltin dilaurate(Desmorapid Z, Bayer MaterialScience AG, Leverkusen, Germany) and 213.07g of a 27% strength solution of tris(p-isocyanatophenyl)thiophosphate inethyl acetate (Desmodur® RFE, product of Bayer MaterialScience AG,Leverkusen, Germany) were initially introduced and heated to 60° C.Thereafter, 42.37 g of 2-hydroxyethyl acrylate were added dropwise andthe mixture was further kept at 60° C. until the isocyanate content hadfallen below 0.1%. Thereafter, cooling was effected and the ethylacetate was completely removed in vacuo. The product was obtained as asemicrystalline solid.

Preparation of Urethane Acrylate 2:2-({[3-(methylsulphanyl)phenyl]carbamoyl}oxy)-ethyl prop-2-enoate):

In a 100 ml round-bottomed flask, 0.02 g of2,6-di-tert-butyl-4-methylphenol, 0.01 g of Desmorapid® Z, 11.7 g of3-(methylthio)phenyl isocyanate were initially introduced and heated to60° C. Thereafter, 8.2 g of 2-hydroxyethyl acrylate were added dropwiseand the mixture was further kept at 60° C. until the isocyanate contenthad fallen below 0.1%. Thereafter, cooling was effected. The product wasobtained as a light yellow liquid.

Example 1 Trifluoroethyl butylcarbamatez

In a 2 l round-bottomed flask, 0.50 g of Desmorapid Z and 498 g ofn-butyl isocyanate were initially introduced and heated to 60° C.Thereafter, 502 g of trifluoroethanol were added dropwise and themixture was further kept at 60° C. until the isocyanate content hadfallen below 0.1%. Thereafter, cooling was effected. The product wasobtained as a colourless solid. The refractive index n²⁰;_(D) determinedby method B is 1.3900 and the measured TGA95 value is 63.7° C.

Further Examples

Examples 2-25 were prepared in the manner described for Example 1, inthe compositions stated in Table 2. The associated n²⁰;_(D) and TGA95values for all examples were measured as described in the abovecorrespondingly named sections.

TABLE 2 Preparation and characterization of Examples 2-35 Exam-Isocyanate and Catalyst and Temp Descrip- ple Name amount Alcohol andamount amount [° C.] tion 2 2,2,2-Trifluoroethyl hexylcarbamate n-Hexylisocyanate Trifluoroethanol Desmorapid Z 60° C. colourless 55.9 g 44.0 g0.05 g liquid 3 2,2,3,3-Tetrafluoropropyl butylcarbamate n-Butylisocyanate 2,2,3,3-Tetra- Desmorapid Z 60° C. colourless 10.7 gfluoropropan-1-ol 0.01 g liquid 14.3 g 4Bis(2,2,2-trifluoroethyl)-(2,2,4- 2,4,4-Trimethylhexane TrifluoroethanolDesmorapid Z 60° C. colourless trimethylhexane-1,6-diyl) biscarbamate1,6-diisocyanate 463 g 0.48 G liquid (TMDI) 496 g 5Bis(2,2,2-trifluoroethyl)-[4- 1,8-Diisocyanato-4-(iso- TrifluoroethanolDesmorapid Z 60° C. colourless ({[(2,2,2-trifluoroethoxy)-cyanatomethyl)octane 272 g 0.48 g liquid carbonyl]amino}methyl)octane-(TIN) 1,8-diyl] biscarbamate 228 g 6 2,2,3,3,4,4,4-Heptafluorobutyln-Butyl isocyanate 2,2,3,3,4,4,4-Hepta- Desmorapid Z 60° C. colourlessbutylcarbamate 24.8 g fluorobutanol 0.04 g solid 50.1 g 72,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9- n-Butyl isocyanate2,2,3,3,4,4,5,5,6,6,7,7,8, Desmorapid Z 60° C. colourlessHexadecafluorononyl butylcarbamate 186 g 8,9,9-Hexadecafluoro- 0.50 gliquid nonanol 813 g 8 Bis(2,2,3,3,4,4,4-heptafluorobutyl)-2,4,4-Trimethylhexane 2,2,3,3,4,4,4-Hepta- Desmorapid Z 60° C.colourless (2,2,4-trimethylhexane-1,6-diyl) 1,6-diisocyanatefluorobutanol 0.01 g liquid biscarbamate (TMDI) 13.1 g 6.88 g 9Bis(2,2,3,3,4,4,4-heptafluorobutyl)-[4- 1,8-Diisocyanato-4-(iso-2,2,3,3,4,4,4-Hepta- Desmorapid Z 60° C. colourless({[(2,2,3,3,4,4,4-heptafluoro- cyanatomethyl)octane fluorobutanol 0.01 goil butoxy)carbonyl]amino}methyl)octane-1,8- (TIN) 14.1 g diyl]biscarbamate 5.91 g 10 2,2,3,3,4,4,5,5,5-Nonafluoropentyl n-Butylisocyanate 2,2,3,3,4,4,5,5,5-Nona- Desmorapid Z 70° C. colourlessbutylcarbamate 4.25 g fluoropentan-1-ol 0.02 g liquid 10.7 g 11Bis(2,2,3,3,4,4,5,5,5-nonafluoropentyl)- 2,4,4-Trimethylhexane2,2,3,3,4,4,5,5,5-Nona- Desmorapid Z 70° C. colourless(2,2,4-trimethylhexane-1,6-diyl) 1,6-diisocyanate fluoropentan-1-ol 0.02g liquid biscarbamate (TMDI) 10.6 g 4.43 g 122,2,3,3,4,4,5,5,5-Nonafluoropentyl n-Hexyl isocyanate2,2,3,3,4,4,5,5,5-Nona- Desmorapid Z 70° C. colourless hexylcarbamate5.05 g fluoropentan-1-ol 0.02 g liquid 9.94 g 132,2,3,3,4,4,5,5,5-Nonafluoropentyl i-Propyl isocyanate2,2,3,3,4,4,5,5,5-Nona- Desmorapid Z 70° C. colourless propan-2-ylcarbamate 3.81 g fluoropentan-1-ol 0.02 g liquid 11.2 g 142,2,3,3,4,4,5,5,6,6,6-Undecafluorohexyl n-Butyl isocyanate2,2,3,3,4,4,5,5,6,6,6- Desmorapid Z 70° C. colourless butylcarbamate3.72 g Undecafluorohexan-1-ol 0.02 g liquid 11.3 g 15Bis(2,2,3,3,4,4,5,5,6,6,6-undecafluoro- 2,4,4-Trimethylhexane2,2,3,3,4,4,5,5,6,6,6- Desmorapid Z 70° C. colourlesshexyl)-(2,2,4-trimethylhexane-1,6-diyl) 1,6-diisocyanateUndecafluorohexan-1-ol 0.02 g oil biscarbamate (TMDI) 11.1 g 3.88 g 162,2,3,3,4,4,5,5,6,6,6-Undecafluorohexyl n-Hexyl isocyanate2,2,3,3,4,4,5,5,6,6,6- Desmorapid Z 70° C. colourless hexylcarbamate4.46 g Undecafluorohexan-1-ol 0.02 g liquid 10.5 g 17Bis(2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoro- 2,4,4-Trimethylhexane2,2,3,3,4,4,5,5,6,6,7,7- Desmorapid Z 70° C. colourlessheptyl)-(2,2,4-trimethylhexane-1,6-diyl) 1,6-diisocyanateDodecafluoroheptan-1-ol 0.02 g oil biscarbamate (TMDI) 11.4 g 3.60 g 182,2,3,3,4,4,5,5,6,6,7,7-Dodecafluoroheptyl n-Hexyl isocyanate2,2,3,3,4,4,5,5,6,6,7,7- Desmorapid Z 70° C. colourless hexylcarbamate4.15 g Dodecafluoroheptan-1-ol 0.02 g liquid 10.8 g 192,2,3,3,4,4,5,5,6,6,7,7-Dodecafluoroheptyl i-Propyl isocyanate2,2,3,3,4,4,5,5,6,6,7,7- Desmorapid Z 70° C. colourlesspropan-2-ylcarbamate 3.06 g Dodecafluoroheptan-1-ol 0.02 g liquid 11.93g 20 2,2,3,3,4,4,5,5,6,6,7,7-Dodecafluoroheptyl Cyclohexyl isocyanate2,2,3,3,4,4,5,5,6,6,7,7- Desmorapid Z 70° C. colourlesscyclohexylcarbamate 4.10 g Dodecafluoroheptan-1-ol 0.02 g liquid 10.9 g21 2,2,3,4,4,4-Hexafluorobutyl butylcarbamate n-Butyl isocyanate2,2,3,4,4,4- Desmorapid Z 70° C. colourless 5.28 g Hexafluorobutan-1-ol0.02 g liquid 9.71 g 22 2,2,3,4,4,4-Hexafluorobutyl hexylcarbamaten-Hexyl isocyanate 2,2,3,4,4,4-Hexafluoro- Desmorapid Z 70° C.colourless 6.16 g butan-1-ol 0.02 g liquid 8.83 g 232,2,3,4,4,4-Hexafluorobutyl propan-2- i-Propyl isocyanate2,2,3,4,4,4-Hexafluoro- Desmorapid Z 70° C. colourless ylcarbamate 4.77g butan-1-ol 0.02 g oil 10.2 g 24 2,2,3,3,4,4,5,5-Octafluoropentyln-Butyl isocyanate 2,2,3,3,4,4,5,5-Octa- Desmorapid Z 70° C. colourlessbutylcarbamate 4.48 g fluoropentan-1-ol 0.02 g liquid 10.5 g 25Bis(2,2,3,3,4,4,5,5-octafluoropentyl)-{4- 1,8-Diisocyanato-4-2,2,3,3,4,4,5,5-Octa- Desmorapid Z 70° C. colourless[({[(2,2,3,3,4,4,5,5-octafluoropentyl)- (isocyanatomethyl)octanefluoropentan-1-ol 0.02 g oil oxy]carbonyl}amino)methyl]octane 1,8- (TIN)11.0 g diyl}biscarbamate 3.98 g 26Bis(2,2,3,3,4,4,5,5-octafluoropentyl)-(2,2,4- 2,4,4-Trimethylhexane2,2,3,3,4,4,5,5-Octa- Desmorapid Z 70° C. colourlesstrimethylhexane-1,6-diyl) biscarbamate 1,6-diisocyanatefluoropentan-1-ol 0.02 g oil (TMDI) 10.3 g 4.67 g 272,2,3,3,4,4,5,5-Octafluoropentyl propan- i-Propyl isocyanate2,2,3,3,4,4,5,5-Octa- Desmorapid Z 70° C. colourless 2-ylcarbamate 4.02g fluoropentan-1-ol 0.02 g liquid 10.9 g 282,2,3,3,4,4,5,5-Octafluoropentyl Cyclohexyl isocyanate2,2,3,3,4,4,5,5-Octa- Desmorapid Z 70° C. colourless cyclohexylcarbamate5.25 g fluoropentan-1-ol 0.02 g liquid 9.73 g 29Bis(2,2,3,3-tetrafluoropropyl)-[4- 1,8-Diisocyanato-4-2,2,3,3-Tetrafluoro-1- Desmorapid Z 70° C. colourless({[(2,2,3,3-tetrafluoro- (isocyanatomethyl)octane propanol 0.02 g oilpropoxy)carbonyl]amino}methyl)octan-1,8- (TIN) 9.16 g diyl] biscarbamate5.83 g 30 Bis(2,2,3,3-tetrafluoropropyl)-(2,2,4- 2,4,4-Trimethylhexane2,2,3,3-Tetrafluoro-1- Desmorapid Z 70° C. colourlesstrimethylhexane-1,6-diyl) biscarbamate 1,6-diisocyanate propanol 0.02 gliquid (TMDI) 8.35 g 6.64 g 31 2,2,3,3-Tetrafluoropropyl propan-i-Propyl isocyanate 2,2,3,3-Tetrafluoro- Desmorapid Z 70° C. colourless2-ylcarbamate 5.87 g propan-1-ol 0.02 g liquid 9.11 g 32 Ethylhexylcarbamate n-Hexyl isocyanate Ethanol Desmorapid Z 60° C. colourless36.7 g 13.3 g 0.02 g liquid 33 iso-Propyl hexylcarbamate n-Hexylisocyanate iso-Propanol Desmorapid Z 60° C. colourless 34.0 g 16.0 g0.02 g liquid 34 3-Ethyl butylcarbamate n-Butyl isocyanate EthanolDesmorapid Z 60° C. colourless 34.1 g 15.9 g 0.02 g liquid 35 iso-Propylbutylcarbamate n-Butyl isocyanate iso-Propanol Desmorapid Z 60° C.colourless 31.1 g 18.9 g 0.02 g liquid

Estimation of the Refractive Index (n_(D) ²⁰) and of the volatility(TGA95) of 2,2,2-trifluoroethyl butylcarbamate Example 1

The three-dimensional structure of the abovementioned compound(Example 1) was generated and preoptimized with the aid of the graphicuser interface of the molecular modelling package Materials Studio ofAccelrys. This preoptimized structure was then used as input for theconformer analysis, for which a Monte Carlo algorithm was used, which,in each case starting from the conformer generated just beforehand,changes all dihedral angles within the molecule according to the randomprinciple. In this way, 1000 random conformers were generated anddirectly preoptimized. In the procedure, all conformers which have arelative energy of >8.37 kJ/mol were directly discarded.

After this procedure, all 90 conformers obtained was subsequentlyoptimized using a more stringent convergence criterion and thensubjected to a similarity analysis, very similar conformers beingdiscarded. The remaining 34 conformers were then optimized geometricallyusing the quantum chemistry package TURBOMOLE with the aid of thedensity functional theory. The B-P86 density functional and the triple ξvalence basis set TZVP, which was taken from the TURBOMOLE basis setlibrary, were used and the COSMO option, using the optimized COSMOradii, was switched on.

For the 22 conformers whose relative DFT/COSMO Energy was <8 kJ/mol, theindividual descriptors V_(i), A_(i), and M² _(i) were subsequentlycalculated according to steps e and f of the method according to theinvention. For this purpose, the COSMOtherm of COSMOlogic was used. Theresults are listed in Table 3.

TABLE 3 Rel. energy Boltzmann Conformer in kJ/mol Weight in % V (Å³) A(Å²) M² 1 0.00 15.92 224.534 224.129 69.717 2 0.14 15.02 224.692 224.47269.698 3 0.46 13.21 223.745 228.546 74.656 4 0.95 10.86 222.437 228.83674.314 5 1.80 7.70 224.267 226.684 73.407 6 1.90 7.39 224.614 226.73873.401 7 3.86 3.35 222.143 224.595 74.151 8 3.96 3.22 223.430 227.02774.845 9 4.09 3.06 224.181 220.790 73.732 10 4.24 2.88 226.841 218.56273.464 11 5.07 2.06 222.067 227.356 72.800 12 5.08 2.05 224.635 224.35972.785 13 5.35 1.84 225.926 217.658 76.949 14 5.58 1.68 227.028 216.15372.131 15 6.32 1.24 222.207 226.866 74.032 16 6.39 1.21 224.162 220.36871.597 17 6.97 0.95 224.831 226.248 75.008 18 7.55 0.76 224.889 222.00671.440 19 7.60 0.74 225.386 223.325 75.264 20 7.72 0.71 225.336 225.14774.730 21 7.88 0.66 221.676 224.815 72.557 22 7.88 0.66 226.532 216.02273.523 This gives the following as Boltzmann-weighted mean values: A =225.308 Å², V = 224.137 Å³, M² = 72.609

It results in the values 85.0° C. and 1.197 g/mol for the volatility(TGA95) and the density.

The molar polarizability was estimated as 40.310 m³/mol with the aid ofthe QSPR approach published in 1986 by Crippen and implemented in theMaterials Studio QSAR module, which, in combination with the density,results in a refractive index of (n_(D) ²⁰)=1.3999. The substance, witha TGA95 value of 85.0° C. and a refractive index of 1.3999, is thereforenot suitable overall in the context of the selection method according tothe invention as an additive for photopolymer formulations since itsestimated volatility is clearly too high. As shown by the comparisonwith experimental values, this evaluation is correct.

The volatilities and refractive indices of Examples 2-39 were calculatedin a manner analogous to that of Example 1 and the results weresummarized in Table 4. A further 30 fluorinated urethanes (Examples2-31), 4 unfluorinated urethanes (Examples 32-35) and four commercialplasticizers (Examples 36-39) are contained therein.

TABLE 4 Comparison of estimated and experimental refractive indices andTGA95 values. Exam- M/ MP/ ρ (n_(D) ²⁰) TGA95 (n_(D) ²⁰) TGA95 ple NameV/Å³ A/Å² M² (g/mol) (m³/mol) (QSPR) (QSPR) (QSPR) (Exp.) (Exp.) 22,2,2-Trifluoroethyl hexylcarbamate 266.609 268.162 76.273 227.23 49.511.146 1.4136 72.2 1.3984 72.5 3 2,2,3,3-Tetrafluoropropyl butylcarbamate254.440 253.494 94.734 231.19 44.09 1.241 1.3893 86.5 1.3879 71.6 4Bis(2,2,2-trifluoroethyl)-(2,2,4- 449.384 412.813 142.624 410.35 83.031.285 1.4333 135.5 1.4202 167.1 trimethylhexane-1,6-diyl) biscarbamate 5Bis(2,2,2-trifluoroethyl)-[4-({[(2,2,2- 571.236 540.825 214.491 551.40103.39 1.384 1.4322 172.5 1.4213 174.9trifluoroethoxy)carbonyl]amino}methyl)- octane-1,8-diyl] biscarbamate 62,2,3,3,4,4,4-Heptafluorobutyl 299.099 285.161 71.344 299.19 49.65 1.3721.3727 75.5 1.3625 69.8 butylcarbamate 72,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9- 476.888 415.268 92.904 531.23 72.101.569 1.3459 116.6 1.3555 111.8 Hexadecafluorononyl butylcarbamate 8Bis(2,2,3,3,4,4,4-heptafluorobutyl)- 606.335 522.310 136.852 610.38101.71 1.432 1.3930 151.5 1.3887 139.1 (2,2,4-trimethylhexane-1,6-diyl)biscarbamate 9 Bis(2,2,3,3,4,4,4-heptafluorobutyl)-[4- 813.142 689.703193.478 851.44 131.40 1.517 1.3846 191.3 1.3876 159.7({[(2,2,3,3,4,4,4-heptafluorobutoxy)- carbonyl]amino}methyl)octane-1,8-diyl] biscarbamate 10 2,2,3,3,4,4,5,5,5-Nonafluoropentyl 336.687311.927 73.341 349.19 54.31 1.433 1.3640 83.5 1.3580 72.8 butylcarbamate11 Bis(2,2,3,3,4,4,5,5,5-nonafluoropentyl)- 683.549 574.484 135.816710.40 111.04 1.484 1.3807 160.5 1.3820 157(2,2,4-trimethylhexane-1,6-diyl) biscarbamate 122,2,3,3,4,4,5,5,5-Nonafluoropentyl 379.492 352.267 73.741 377.25 63.521.369 1.3780 89.9 1.3690 83.5 hexylcarbamate 132,2,3,3,4,4,5,5,5-Nonafluoropentyl 315.705 289.954 70.340 335.17 49.611.469 1.3541 79.0 1.3497 58.5 propan-2-ylcarbamate 142,2,3,3,4,4,5,5,6,6,6-Undecafluorohexyl 374.581 335.864 68.869 399.2058.98 1.479 1.3560 87.7 1.3538 82.6 butylcarbamate 15Bis(2,2,3,3,4,4,5,5,6,6,6- 757.048 613.121 134.098 810.41 120.38 1.5361.3736 169.4 1.3750 152.7 undecafluorohexyl)-(2,2,4-trimethyl-hexane-1,6-diyl) biscarbamate 16 2,2,3,3,4,4,5,5,6,6,6-Undecafluorohexyl416.853 379.371 73.759 427.25 68.18 1.419 1.3704 96.4 1.3640 90hexylcarbamate 17 Bis(2,2,3,3,4,4,5,5,6,6,7,7- 811.336 671.039 176.795874.44 127.93 1.560 1.3739 187.5 1.3839 158.6dodecafluoroheptyl)-(2,2,4- trimethylhexane-1,6-diyl) biscarbamate 182,2,3,3,4,4,5,5,6,6,7,7-Dodecafluoroheptyl 445.778 401.101 94.859 459.2771.96 1.440 1.3690 112.1 1.3716 117.6 hexylcarbamate 192,2,3,3,4,4,5,5,6,6,7,7-Dodecafluoro- 381.492 338.779 91.463 417.1958.05 1.534 1.3470 103.0 1.3563 93.3 heptylpropan-2-yl carbamate 202,2,3,3,4,4,5,5,6,6,7,7-Dodecafluoroheptyl 430.049 369.790 83.268 457.2569.90 1.491 1.3731 105.9 1.3830 123.7 cyclohexylcarbamate 212,2,3,4,4,4-Hexafluorobutyl 291.826 273.825 90.643 281.20 49.25 1.3321.3829 90.0 1.3775 73.8 butylcarbamate 22 2,2,3,4,4,4-Hexafluorobutyl335.639 313.390 92.270 309.25 58.45 1.271 1.3959 95.5 1.3876 89.5hexylcarbamate 23 2,2,3,4,4,4-Hexafluorobutyl propan-2- 269.738 259.02991.749 267.17 44.54 1.368 1.3733 87.7 1.3682 71.5 ylcarbamate 242,2,3,3,4,4,5,5-Octafluoropentyl 330.134 303.188 88.913 331.20 53.421.393 1.3674 93.7 1.3731 80.5 butylcarbamate 25Bis(2,2,3,3,4,4,5,5-octafluoropentyl)-{4- 895.878 763.826 254.799 947.50142.73 1.552 1.3840 215.0 1.3955 172.5[({[(2,2,3,3,4,4,5,5-octafluoropentyl)-oxy]carbonyl}amino)methyl]octane-1,8- diyl} biscarbamate 26Bis(2,2,3,3,4,4,5,5-octafluoropentyl)- 667.015 566.787 174.890 674.42109.26 1.457 1.3880 172.4 1.3971 163.9 (2,2,4-trimethylhexane-1,6-diyl)biscarbamate 27 2,2,3,3,4,4,5,5-Octafluoropentyl propan-2- 308.600286.261 90.842 317.18 48.72 1.429 1.3577 92.3 1.3654 74.4 ylcarbamate 282,2,3,3,4,4,5,5-Octafluoropentyl- 355.202 319.977 87.653 357.24 60.561.400 1.3905 96.7 1.3977 110.5 cyclohexylcarbamate 29Bis(2,2,3,3-tetrafluoropropyl)-[4- 668.003 606.741 275.686 647.45 114.731.417 1.4162 202.8 1.4240 197.9 ({[(2,2,3,3-tetrafluoropropoxy)-carbonyl]amino}methyl)octane-1,8- diyl]biscarbamate 30Bis(2,2,3,3-tetrafluoropropyl)-(2,2,4- 517.127 461.959 184.103 474.3990.59 1.313 1.4155 161.6 1.4229 185.3 trimethylhexane-1,6-diyl)biscarbamate 31 2,2,3,3-Tetrafluoropropyl propan-2- 234.335 231.84593.129 217.16 39.38 1.268 1.3770 85.2 1.3831 78.1 ylcarbamate 32 Ethylhexylcarbamate 241.340 247.593 72.851 173.26 48.81 0.941 1.4431 65.51.4376 83.9 33 iso-Propyl hexylcarbamate 264.827 264.082 70.384 187.2853.23 0.930 1.4413 67.9 1.4336 84.9 34 3 Ethyl butylcarbamate 197.717207.505 71.325 145.20 39.61 0.960 1.4367 59.2 1.4313 66.1 35 iso-Propylbutylcarbamate 220.538 224.943 68.619 159.23 44.03 0.946 1.4361 60.11.4284 63.9 36 Propylene carbonate 115.733 128.139 71.612 102.09 21.491.167 1.4059 64.3 1.4210 87 37 Dimethyl adipate 221.881 226.334 97.343174.20 42.28 1.055 1.4256 86.5 1.4280 80.4 38 Diethylene glycoldiacetate 231.636 242.845 113.550 190.19 43.90 1.110 1.4261 97.9 1.430099.1 39 Triethyl citrate 328.385 305.298 134.859 276.28 64.18 1.1741.4575 123.9 1.4420 131Comparison between Experimental and Estimated TGA95 and Refractive IndexValues

The comparison between the experimental refractive indices and TGA95values of Examples 1-39 and those estimated by the selection methodaccording to the invention (Table 4), which is illustrated in thecorrelation diagrams in FIG. 3 and FIG. 4, clearly show the suitabilityof the method. The refractive indices could be determined with astandard deviation of 0.0082, the maximum error over the total set, withan absolute value of 0.0155 for Example 39, likewise being very small.The standard deviation for the TGA95 values is 15.8° C., with anabsolute maximum error of 42.5° C. for the fluorinated urethane ofExample 25. However, this comparatively large error is not significantsince both the experimental value of 172.5° C. and the estimated valueof 215.0° C. are substantially above the suitability limit of 100° C.Thus, in spite of the error, the compound is correctly classed by themethod according to the invention as being suitable as an additive forphotopolymer formulations. In general, it may be stated that very largedifferences between predicted and experimental TGA95 typically occur inthe case of comparatively high absolute values (typically >150° C.),which is attributable to incipient decomposition of the substances. Thisfact does not imply any limitation of the informative power of theselection method according to the invention since the threshold valuefor the suitability of the substance at 100° C. is typically well belowthe decomposition temperature of customary additive molecules.

Selection of the Example Molecules on the Basis of the Method Accordingto the Invention

The refractive indices of Examples 1-39 are all below 1.4600. In thiscase, the TGA95 estimated by the method according to the invention aretherefore decisive regarding the suitability as additives inphotopolymer formulations. All examples whose estimated volatility,according to TGA95, is greater than 100° C. are summarized in Table 5.

TABLE 5 Additives selected according to the invention. (n_(D) ²⁰) TGA95(n_(D) ²⁰) TGA95 Example (QSPR) (QSPR) (Exp.) (Exp.) 4 1.4333 135.51.4202 167.1 5 1.4322 172.5 1.4213 174.9 7 1.3459 116.6 1.3555 111.8 81.3930 151.5 1.3887 139.1 9 1.3846 191.3 1.3876 159.7 11 1.3807 160.51.3820 157.0 15 1.3736 169.4 1.3750 152.7 17 1.3739 187.5 1.3839 158.618 1.3690 112.1 1.3716 117.6 19 1.3470 103.0 1.3563 93.3 20 1.3731 105.91.3830 123.7 25 1.3840 215.0 1.3955 172.5 26 1.3880 172.4 1.3971 163.929 1.4162 202.8 1.4240 197.9 30 1.4155 161.6 1.4229 185.3 39 1.4575123.9 1.4420 131.0

Examples 7 and 17 which, owing to their low refractive indices and thesufficiently high volatility, should be very efficient are selected foran experimental investigation of the holographic activity. The compound2 which, with an estimated volatility of 72.2° C., is substantiallyoutside the limits of the method according to the invention is selectedas a comparative example.

Preparation of the Photopolymer Formulation for the Production ofHolographic Films Film Example 1

6.77 g of the polyol component prepared as described above were mixedwith 4.00 g ofphosphorothioyltris(oxybenzene-4,1-diylcarbamoyloxyethane-2,1-diyl)trisacrylate(urethane acrylate 1), 4.00 g of2-({[3-(methylsulphanyl)phenyl]carbamoyl}oxy)propylprop-2-enoate(urethane acrylate 2) 3.00 g of2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9-hexadecafluorononyl butylcarbamate(Example 7), 0.02 g of Fomrez UL 28 (urethanization catalyst, commercialproduct of Momentive Performance Chemicals, Wilton, Conn., USA), 0.30 gof CGI 909 (experimental product of Ciba Inc, Basle, Switzerland), 0.03g of new methylene blue, 0.06 g of BYK 310 and 1.02 g ofN-ethylpyrrolidone at 60° C. so that a clear solution was obtained.Thereafter, cooling to 30° C. was effected, 1.25 g of Desmodur® N3900(commercial product of Bayer MaterialScience AG, Leverkusen, Germany,hexane diisocyanate-based polyisocyanate, proportion ofiminooxadiazinedione at least 30%, NCO content: 23.5%) were added andmixing was effected again. The liquid material obtained is then appliedby means of a knife coater to a 36 μm thick polyethylene terephthalatefilm and dried for 4.5 minutes at 80° C. in an air circulation dryer.Thereafter, the photopolymer layer is covered with a 40 μm thickpolyethylene film and rolled up.

Film Example 2

6.77 g of the polyol component prepared as described above were mixedwith 4.00 g ofphosphorothioyltris(oxybenzene-4,1-diylcarbamoyloxyethane-2,1-diyl)trisacrylate(urethane acrylate 1), 4.00 g of2-[({3-(methylsulphanyl)phenyl]carbamoyl}oxy)propylprop-2-enoate(urethane acrylate 2) 3.00 g ofbis(2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl)-(2,2,4-trimethylhexane-1,6-diyl)biscarbamate(Example 17), 0.02 g of Fomrez UL 28 (urethanization catalyst,commercial product of Momentive Performance Chemicals, Wilton, Conn.,USA), 0.30 g of CGI 909 (experimental product of Ciba Inc, Basle,Switzerland), 0.03 g of new methylene blue, 0.06 g of BYK 310 and 1.02 gof N-ethylpyrrolidone at 60° C. so that a clear solution was obtained.Thereafter, cooling to 30° C. was effected, 1.25 g of Desmodur® N3900(commercial product of Bayer MaterialScience AG, Leverkusen, Germany,hexane diisocyanate-based polyisocyanate, proportion ofiminooxadiazinedione at least 30%, NCO content: 23.5%) were added andmixing was effected again. The liquid material obtained is then appliedby means of a knife coater to a 36 μm thick polyethylene terephthalatefilm and dried for 4.5 minutes at 80° C. in an air circulation dryer.Thereafter, the photopolymer layer is covered with a 40 μm thickpolyethylene film and rolled up.

Comparative Film Example I

6.77 g of the polyol component prepared as described above were mixedwith 4.00 g ofphosphorothioyltris(oxybenzene-4,1-diylcarbamoyloxyethane-2,1-diyl)trisacrylate(urethane acrylate 1), 4.00 g of2-({[3-(methylsulphanyl)phenyl]carbamoyl}oxy)propylprop-2-enoate(urethane acrylate 2) 3.00 g of 2,2,2-trifluoroethyl butylcarbamate(Example 1), 0.02 g of Fomrez UL 28 (urethanization catalyst, commercialproduct of Momentive Performance Chemicals, Wilton, Conn., USA), 0.30 gof CGI 909 (experimental product of Ciba Inc, Basle, Switzerland), 0.03g of new methylene blue, 0.06 g of BYK 310 and 1.02 g ofN-ethylpyrrolidone at 60° C. so that a clear solution was obtained.Thereafter, cooling to 30° C. was effected, 1.25 g of Desmodur® N3900(commercial product of Bayer MaterialScience AG, Leverkusen, Germany,hexane diisocyanate-based polyisocyanate, proportion ofiminooxadiazinedione at least 30%, NCO content: 23.5%) were added andmixing was effected again. The liquid material obtained is then appliedby means of a knife coater to a 36 μm thick polyethylene terephthalatefilm and dried for 4.5 minutes at 80° C. in an air circulation dryer.Thereafter, the photopolymer layer is covered with a 40 μm thickpolyethylene film and rolled up.

TABLE 6 Holographic evaluation of film examples Example, [% by weight]Δn Film Example 1 7, 15 0.038 2 17, 15  0.032 Comparative film example 12, 15 0.012

The values described by Δn were obtained at doses of 4-32 ml/cm².

The values found for the holographic property Δn of the holographicmedia show that the additives selected by the method according to theinvention are better suited for use in holographic photopolymer films.

1.-11. (canceled)
 12. A method for selecting compounds which can be usedas plasticizers in photopolymer formulations for the production of lightholographic media, wherein the method comprises: a) selecting a compoundto be tested, b) carrying out a conformer analysis of the compound to betested using a suitable computer programme, c) generating anoptimization of the geometry of all conformers with the aid of a forcefield method and the conformer space is then further reduced with theaid of a similarity analysis, d) effecting a quantum chemicaloptimization of the geometry of the conformers which are energeticallymost favourable according to the force field optimization with the useof the B-P86 density functional and a triple □ valence basis set, and ofthe Conductor Like Screening Model (COSMO) in combination with theoptimized COSMO radii or, if these do not exist for a given element,with 1.17 times the Bondi valence radius, e) calculating the area (A) inÅ² and the enclosed volume (V) in Å³ of the three-dimensional COSMOshielding charge density surfaces of the conformers having the lowestenergy, which are obtained as result of the quantum chemicaloptimization of the geometry, f) dividing into segments, the COSMOshielding charge density surfaces of the conformers having the lowestenergy with the aid of a suitable software package, the mean surfaceshielding charge density (□) of these segments are plotted in the formof a frequency distribution P(□) and the second moments (M²) of thisdistribution, defined according to the equation:$M^{2} = {10 \cdot {\sum\limits_{i}\; {{P\left( \sigma_{i} \right)} \cdot \sigma_{i}^{2} \cdot {\Delta\sigma}}}}$ are determined, □□ being the interval width of the discrete frequencydistribution and the charge densities □ being stated in the unit e/nm²,g) averaging the volumes, areas and second moments of all conformersconsidered according to their weight in the Boltzmann distribution onthe basis of the energies obtained from the quantum chemicaloptimizations of the geometries, h) estimating the volatility of thesubstance according to the computational rule:${{{TGA}\; 95} \approx {{207.015 \cdot \frac{M^{2}}{A}} + {41.405 \cdot \sqrt[3]{V}} - 253.2}},$i) estimating the density of the compound at room temperature with theaid of the equation:$\rho = {{0.89 \cdot \frac{M}{V \cdot N_{A}}} - {0.2 \cdot \frac{A}{V}} + {0.01 \cdot \sqrt{M^{2}}}}$ □ being the density of the pure substance in g/cm³, M being the molarmass in g/mol, N_(A) being the Avogadro number, A being the COSMOshielding charge density surface in Å², V being the volume in Å³enclosed by the surface and M² being the second moment of the surfaceshielding charge density frequency distribution, j) using the estimateddensity in order, with the aid of the Lorentz-Lorenz equation:${n_{D} = \sqrt{\frac{{2 \cdot \frac{\rho \cdot {MP}}{M}} + 1}{1 - \frac{\rho \cdot {MP}}{M}}}},$ to convert the molar polarizability (MP) estimated according to a QSPRapproach as accurately as possible into a refractive index at 589 nm(n_(D) ²⁰) k) determining whether the volatility of the compound to betested is >100° C. and the refractive index thereof is ≦1.4600, thecompound to be tested being classed as being suitable if both conditionsare fulfilled.
 13. The method according to claim 12, wherein, in stepb), the computer program used to carry out the conformer analysis is theconformers module of the Materials Studio program package of Accelrys.14. The method according to claim 12, wherein, in step f), the suitablesoftware package is the program COSMOtherm of COSMOlogic.
 15. The methodaccording to claim 12, wherein, in step d), a quantum chemicaloptimization of the geometry of the conformer having the lowest energyaccording to the force field optimization is effected.
 16. The methodaccording to claim 12, wherein, in step d), a quantum chemicaloptimization of the geometry of all conformers in an energy window of0-4 kJ/mol according to the force field optimization is effected. 17.The method according to claim 12, wherein, in step d), a quantumchemical optimization of the geometry of all conformers in an energywindow of 0-8 kJ/mol according to the force field optimization iseffected.
 18. The method according to claim 12, wherein, in step k), acheck is carried out to determine whether the volatility of the compoundto be tested is >120° C. and the refractive index thereof nD is ≦1.4500.19. The method according to claim 12, wherein, in step k), a check iscarried out to determine whether the volatility of the compound to betested is >120° C. and the refractive index thereof nD is ≦1.4400. 20.The method according to claim 12, wherein, in step k), a check iscarried out to determine whether the volatility of the compound to betested is >120° C. and the refractive index thereof nD is ≦1.4300.
 21. Aphotopolymer formulation comprising matrix polymers, writing monomersand photoinitiators, wherein the photopolymer formulation furthercomprises at least one plasticizer which is selected by the methodaccording to claim 12 and wherein the matrix polymers comprisepolyurethanes.
 22. The photopolymer formulation according to claim 21,wherein the photoinitiators comprise an anionic, cationic or neutral dyeand a coinitiator.
 23. The photopolymer formulation according to claim21, wherein the at least one plasticizer comprises urethanes, andwherein the urethane is capable of being substituted by at least onefluorine atom.
 24. The photopolymer formulation according to claim 23,wherein the urethanes have the formula (II)

wherein n is from 1 to 8 and R¹, R², R³ represent, independently of oneanother, hydrogen or linear, branched, cyclic or heterocyclic organicradicals which are unsubstituted or optionally also substituted byheteroatoms.
 25. The photopolymer formulation according to claim 24,wherein at least one of the radicals R1, R2, R3 is substituted by atleast one fluorine atom.
 26. The photopolymer formulation according toclaim 24, wherein R1 represents an organic radical having at least onefluorine atom.
 27. The photopolymer formulation according to claim 21,wherein the writing monomers comprise a monofunctional acrylate of theformula (IV)

wherein R⁷, R⁸, independently of one another, represent hydrogen orlinear, branched, cyclic or heterocyclic organic radicals which areunsubstituted or optionally also substituted by heteroatoms.
 28. Thephotopolymer formulation according to claim 21, wherein the writingmonomers comprise a polyfunctional writing monomer.
 29. The photopolymerformulation according to claim 21, wherein, the writing monomerscomprise a polyfunctional acrylate.
 30. The photopolymer formulationaccording to claim 29, wherein the polyfunctional acrylate has theformula (V)

wherein n is from 2 to 4 and R⁹, R¹⁹, independently of one another,represent hydrogen or linear, branched, cyclic or heterocyclic organicradicals which are unsubstituted or optionally also substituted byheteroatoms.
 31. A method comprising producing in-line holograms,off-axis holograms, full-aperture transfer holograms, white lighttransmission holograms, Denisyuk holograms, off-axis reflectionholograms, edge-lit holograms or holographic stereograms, wherein theholograms or stereograms are produced with the photopolymer formulationaccording to claim 21.